Header connectors intended for the connection of the patterns printed on a back panel (or backplane) with external circuits by means of contacts inserted in the through holes formed in the back panel, have been used in the art for a long time. The contacts used in such header connectors are usually of a press-fit pin type or are of a compliant pin type having a spring-loaded section which can yield in the direction of the through hole diameter.
With reference to FIGS. 1 and 2, the design of a back panel assembly in which a header connector with press-fit pins is used. FIG. 1 is a partially sectioned view of a back panel assembly having header connectors mounted on its both surfaces with contacts extending in opposite directions; whereas FIG. 2 is a partially sectioned view of a back panel assembly having header connectors mounted on the both sides of the back panel, with the header connectors having common contacts.
The assembly of a double-sided back panel assembly 10 shown in FIG. 1 is carried out as follows: header connectors 16 are mounted on one side 14 of the back panel 12; after that, header connectors 20 are mounted on the other side 18 at a pre-determined pitch (see Japanese Patent Disclosure Sho 63 (1988)-228697). The assembly of a common contacts type back panel assembly 30 shown in FIG. 2 is carried out as follows: header connectors 16 are mounted on one side 14 of a back panel 12; after that, housings 32 are pressed on the ends of the press-fit pins 16a protruding from the other side 18 of the back panel.
Conventional back panel assemblies described above commonly have the following disadvantages: in the double-sided back panel assembly shown in FIG. 1, press-fit pins 16a of the header connectors 16 mounted on the one side 14 of the back panel go through the back panel 12 and extend to the other side 18 of the back panel 12. Therefore, it is necessary to select such a mounting pitch of the housings 20a of the head connectors 20 which are mounted to the other side 18 that they do not interfere with the press-fit pins 16a of the header connectors 16, thus limiting potentials for an increase in the density of the header connectors mounting.
Considerations were given to a technology making it possible to increase the mounting density of header connectors consisting in the use of press-fit pins 16a which do not extend to the other side 18. For this purpose, header connectors with press-fit pins having short contacting portions are used (not shown), and since the tips of the press-fit pins do not extend beyond the through hole, it is possible to achieve much higher mounting density of the header connectors. However, if a press-fit pin is bent and must be replaced with a good one, the bent press-fit pin can be removed from the back panel by pushing on the tip secured in the panel. Also, in the technology described above, in some cases, access to the tip of a damaged press-fit pin is blocked by another connector housing making it impossible to remove the contact from the back panel by pressing on its tip.
Another problem relates to the fact that the assembly process of a double-sided back panel assembly 10 shown in FIG. 1 is more difficult than in a case when header connectors are driven only in one direction relative to the back panel, because header connectors must be fixed to both sides 14, 18 of the back panel 12, resulting in necessity of using rather complicated jigs to support back panels 12 during the work.
Common-contact type back panel assembly 30 shown in FIG. 2 makes it possible to nearly double the mounting density of the header connectors compared to the back panel assembly 10 shown in FIG. 1. However, since the press-fit pins in opposed housings must have common functions, the devices to which the press-fit pins used for signal lines are connected at the side 14 of the back panel and to which they are connected on the other side 18, must be appropriately distributed. Therefore, the limitations imposed on the number of signal lines are even stronger than in the case of double-sided back panel assembly 10 shown in FIG. 1. As a result, the scale of the circuits which can be accommodated on a back panel with mounted header connectors is rather small, thus reducing the effectiveness of the mounting of header connectors.
The problem to be solved by this invention is to offer a header connector making it possible to replace damaged contacts, without compromising the density of connector mounting.
Another problem to be solved by this invention is to offer a back panel assembly with an increased effectiveness of the header connectors mounting.
Finally, it is the intention of this invention is to offer a method of assembly of back panel assemblies consisting of relatively easy operations.